I've been using Photoshop for over 7 years now, and I'm quite comfortable with working with it now. The secret to learning how to use any program, is actually using it. Practise everyday, even if you don't really know what you're doing. Watch lots of YouTube tutorials, but also feel free to experiment. You should allocate at least an hour everyday to messing around with all the different tools in Photoshop. The most important part, however, is enjoying what you're doing. If you're not interested in photography/photo manipulation/graphic design, there's no point in forcing yourself to learn a skill that you're never going to use.